Many designs for lightweight composite structural elements having a thin outer shell and a light core structure are known for both metal and plastic constructions. A large part of the mechanical loads is absorbed by the shell. The primary function of the core structure is to support the shell, and it protects the shell from denting, buckling, etc. Rigid foams and honeycomb geometries are used as core structures, which are mechanically fixed to the shell, often by bonding. Depending on the type and direction of the structural-element loading, rib-like, spar-like, and stringer-like core structures are also used, particularly in the case of a pure metallic construction.
German Published Patent Application No. 40 41 104 describes a blade for turbo engines, which is of a lightweight construction and includes a blade shell and a blade core, the latter being made of a bundle of tubes that are rigidly connected to each other and the outer shell.
The mentioned methods of construction are indeed distinguished by light weight and high flexural stiffness, but their inherent damping in the case of dynamic loading/excitation is, as a rule, low. Blades and structures in turbo engines are subjected to high dynamic loads. Therefore, a high degree of inherent damping of the structural element is advantageous and determines its service life, especially in the case of unavoidable resonance states.
Therefore, it is an object of the present invention to provide a lightweight composite part for turbo engines, which has a low structural weight, high structural stiffness, and a high degree of inherent damping, and is therefore suitable for high dynamic loads.